Animal Nutrition I (Ch. 41)

Keywords

• Heterotroph• Autotroph• Herbivore• Carnivore• Omnivore• Intracellular digestion• Food vacuole• Extracellular digestion

• Gastrovascular cavity• Alimentary canal• Basic parts of

alimentary canal• Roles of mouth and

stomach in digestion

Some of the best known and fascinating adaptations of

animals involve their feeding and digestion

Examples:

• Reptile swallowing prey

• Baleen whales

Python

Starfish

Chiasmodon niger

Cryptopsaras couesi

Eurypharynx pelecanoides

Categories

• I. Autotroph

• II. Heterotroph– A. Herbivore– B. Carnivore– C. Omnivore

Today we’ll focus on heterotrophs:Digestion

• Basic principles

• Invertebrates

• Humans

Why is digestion necessary?

• Macromolecules cannot easily enter cell

COO-NH3+ cytoplasm

Cell membranepeptide

Small molecules such as amino acids can

cytoplasm

Cell membranePeptide being digested

cytoplasm

Cell membranePeptide being digested

cytoplasm

Cell membranePeptide being digested

cytoplasm

Cell membranePeptide being digested

cytoplasm

Cell membrane

Digested peptide

Even if macromolecules are taken in…

COO-NH3+ cytoplasm

Cell membranepeptide

Even if macromolecules are taken in…

COO-NH3+

cytoplasm

Cell membrane

peptide

They cannot be readily incorporated

COO-NH3+

cytoplasm

Cell membrane

Food peptideNew peptide

Unless broken down first

cytoplasm

Cell membrane

Food peptideNew peptide

Unless broken down first

cytoplasm

Cell membrane

Food peptideNew peptide

Unless broken down first

cytoplasm

Cell membrane

Food peptideNew peptide

This lecture will focus on how animals break down food

• I. Intracellular digestion– A. food vacuoles

• II. Extracellular digestion– A. outside organism– B. gastrovascular cavity– C. alimentary canal

I. Intracellular digestion

• A. food vacuoles

Intracellular digestion without vacuoles

Intracellular digestion without vacuoles

Intracellular digestion with vacuoles

Intracellular digestion with vacuoles

Intracellular digestion with vacuoles

Digestion in Paramecium

Intracellular digestionvs.

Extracellular digestion

Extracellular digestion

• A. outside organism

• B. gastrovascular cavities

• C. alimentary canal

Extracellular digestion

• A. outside organism

• B. gastrovascular cavities

• C. alimentary canal

Gastrovascular cavity: Hydra

Extracellular digestion

• A. outside organism

• B. gastrovascular cavities

• C. alimentary canal

Gastrovascular cavity vs. Alimentary Canal

Alimentary canal: a simple view

mouth

Mechanicaldigestion storage

absorption

anus

Basic parts of alimentary canal

Alimentary canal: mammalian

Mouth

• Mechanical

• enzymatic

Stomach

Digestive mechanisms in

stomach

• Mechanical

• Chemical

• enzymatic